Surveying instrument and electronic storage medium

ABSTRACT

The present invention relates to a surveying instrument for measuring the distance to a target to be measured, a horizontal angle, and a vertical angle by use of reflected light. An imager can be connected to the surveying instrument. In addition, an arithmetic processing means can determine a three-dimensional position of a plane part by determining from at least three measuring points an equation that includes the plane part as the target to be measured, and then by associating digital image data to which the plane part belongs with the equation so that the plane part is identified.

TECHNICAL FIELD

The present invention relates to a surveying instrument and anelectronic storage medium, and more particularly to non-prismmeasurement that is capable of measuring a measuring point in corners.

BACKGROUND ART

A technique for performing three-dimensional measurement by use of anon-prism type total station (surveying instrument), which does not usea reflection member such as a corner cube, has been developed.

However, the problem to be solved was that, for example, when theoutward appearance of a building is measured, it was extremely difficultto measure the edges (corners) of the building. Because the measurementis performed by use of a measuring light beam such as a laser light beamwhich is emitted from a non-prism type total station (surveyinginstrument), it is difficult to measure the edge.

DISCLOSURE OF INVENTION

The present invention has been devised taking the above-mentionedproblem into consideration. An object of the present invention is toprovide a surveying instrument for measuring the distance to a target tobe measured, a horizontal angle, and a vertical angle by use ofreflected light. An imager can be connected to the surveying instrument.In addition, an arithmetic processing means can determine athree-dimensional position of a plane part by determining from at leastthree measuring points an equation that includes the plane part as thetarget to be measured, and then by associating digital image data towhich the plane part belongs with the equation so that the plane part isidentified.

According to the present invention, it is also possible to determine athree-dimensional position of the plane part by extracting edges of atleast two intersecting straight lines forming the plane part, and bydetermining the straight lines using the least-squares method or theconditional least-squares method on the basis of image data of theedges, and then by calculating an intersection point of the straightlines.

According to the present invention, if at least two plane partssuccessively intersect with each other, edges of three straight linesforming the angle are extracted, and on the basis of image data of theedges, the straight lines are determined by the least-squares method orthe conditional least-squares method, and then the angle which is anintersection point of the straight lines is calculated to determine athree-dimensional position of the plane part.

According to the present invention, if the plane part includes astraight line, a position and the length of the straight line can alsobe calculated by specifying the straight line.

According to the present invention, if the plane part has a windowbordered by straight lines, the window is specified to identify thewindow, which makes it possible to calculate a position and a shape ofthe window.

According to the present invention, if there is a point located on theplane part which is the target to be measured, it is also possible todetermine the three-dimensional position by determining acenter-of-gravity position of image data of the point, and then byassociating the center-of-gravity position with the three measuringpoints.

According to the present invention, if the surveying instrument facesthe target to be measured, it is also possible to calculate athree-dimensional position of the plane part by determining from ameasured value of one point an equation which includes the plane part asthe target to be measured, and then by associating digital image data towhich the plane part belongs with the equation so that the plane partcan be identified.

According to the present invention, a straight line or a window, whichis included in a plane part, can also be specified by the collimation ofa telescope included in the surveying instrument.

According to the present invention, a straight line or a window, whichis included in the plane part, can also be specified by pointing animage displayed on a display unit included in the surveying instrument.

In addition, the edges can also be extracted by use of a spatial filtersuch as Laplacian.

A three-dimensional measurement method according to the presentinvention is used in a surveying instrument for measuring the distanceto a target to be measured, a horizontal angle, and a vertical angle byuse of reflected light. The surveying instrument is so devised that animager for obtaining a digital image in a measurement direction can beconnected to the surveying instrument. The three-dimensional measurementmethod-comprises the following steps: a first step for determining atleast three measuring points of a plane part, and then for measuring themeasuring points; a second step for determining an equation, whichincludes the plane part, from data of the distance and the angles of thethree measuring points that have been obtained by the measurements; anda third step for associating the digital image data to which the planepart belongs with the equation. A three-dimensional position of theplane part can be determined from the image data that identifies theplane part and from the equation that includes the plane part.

An electronic storage medium such as a FD, a CD, a DVD, a RAM, a ROM, ora memory card is used when three-dimensional measurement is performed byuse of data obtained from a surveying instrument and an imager, whichmeasure the distance to a target to be measured, a horizontal angle, anda vertical angle using reflected light. As a result of executing anarithmetic processing means, it is possible to determine athree-dimensional position of a plane part by determining from at leastthree measuring points an equation that includes the plane part as thetarget to be measured, and then by associating digital image data towhich the plane part belongs with the equation so that the plane partcan be identified.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating the principles of this embodiment;

FIG. 2 is a diagram illustrating the principles of this embodiment;

FIG. 3 is a diagram illustrating the principles of this embodiment;

FIG. 4 is a diagram illustrating the principles of this embodiment;

FIG. 5 is a diagram illustrating the principles of this embodiment;

FIG. 6 is a diagram illustrating the principles of this embodiment;

FIG. 7 is a diagram illustrating the principles of this embodiment;

FIG. 8 is a diagram illustrating a surveying instrument 1000 accordingto the embodiment of the present invention;

FIG. 9 is a diagram illustrating a surveying instrument 1000 accordingto the embodiment of the present invention;

FIG. 10 is a diagram illustrating a telescope unit 4;

FIG. 11 is a diagram illustrating the operation of this embodiment; and

FIG. 12 is a diagram illustrating the principles of this embodiment.

BEST MODES FOR CARRYING OUT THE INVENTION

Principles

Here, the principles will be described using an example in which asshown in FIGS. 1 and 2, three-dimensional coordinates (X, Y, Z) of acorner part 2000 a of a building 2000 which is a target to be measuredare measured. The principles are described by use of the building 2000having planes formed of straight lines, and the like, which seem to be amain usage pattern of the present invention.

To begin with, as shown in FIG. 1, a surveying instrument which isplaced at a reference point O, coordinates of which are known,collimates a α surface forming the building 2000. Three points(preliminary measuring points) substantially forming a triangle on the αsurface are chosen, and then the distance to each point, a horizontalangle, and a vertical angle are measured.

On the basis of measured data, an equation of a plane which includes thepreliminary measuring points is calculated. The plane which includes thepreliminary measuring points includes the α surface.

It is to be noted that the measurement of a plane of a building or thelike using a non-prism type surveying instrument is described inJapanese Patent Application Laid-Open No. Hei 2000-97703 by theapplicant of the application concerned.

In addition to the measurement, digital image data of the building 2000which is the object to be measured is obtained by the imager 100.

In a configuration in which an image is coaxial with the collimation,the center of the collimation coincides with the center of the image.Accordingly, a position in the image can be expressed as horizontal andvertical angles relative to the center of the collimation.

On the basis of the horizontal angle data and the vertical angle datarelative to the center of the collimation center, the position in theimage is calculated by the horizontal angle and the vertical angle.

An image pickup element such as an image sensor, which is used to obtaindigital image data, is constituted of pixels that are arrayed in amatrix. A position of each pixel arranged in the image is known.

When a corner of a building formed of straight lines is determined, anequation of the straight lines is derived from the least-squares methodor the conditional least-squares method on the basis of variations inlight receiving of each pixel, and thereby it is possible to determine aposition of an intersection point in the image as well as horizontal andvertical angles relative to the center of the image. The determinedhorizontal and vertical angles coincide with a horizontal angle and avertical angle of the corner of the building on a α surface relative tothe center of the collimation. Because the horizontal angle data and thevertical angle data of the center of the collimation are known,horizontal angle data and vertical angle data of the angle of thebuilding can be immediately determined. If the distance from the centerof the collimation is measured, it is possible to determine athree-dimensional position of the corner of the building by use of thedetermined equation of the α surface.

Incidentally, if the image is not coaxial with the collimation, propercorrections can also be made.

A first image pickup element 110 picks up a wide-angle image; and asecond image pickup element 120 picks up a narrow-angle image. Thewide-angle image and the narrow-angle image are associated with eachother. The wide-angle image is suitable for the whole image or aclose-range view; and the narrow-angle image is suitable for, forexample, a magnified image, or a distant view.

Incidentally, if the magnification of the telescope can be zoomed in orout, one image pickup element can also be used as both the first imagepickup element 110 and the second image pickup element 120.

In addition, an image of the telescope in proximity to the preliminarymeasuring point A is as shown in FIG. 2. Accordingly, aligning the imagewith a cross line also makes it possible to determine a preliminarymeasuring point in proximity to the window.

A position in the digital image is associated with measured data of thepreliminary measuring point by surveying. The α surface to which thepreliminary measuring point belongs is bordered by straight lines tothereby form a surface. When a position of the building is identified,more specifically, when a coordinate position is identified to surveythe building, since the building is shaped like a box in many cases,identifying corners makes it possible to easily obtain its coordinates.

To begin with, edges of the straight lines forming the α surface ofimage data are extracted by image processing. With the object of theextraction of the edges, for example, a spatial filter such as theLaplacian is used to emphasize the edges. This Laplacian emphasizes theedges using a differential image.

Next, two straight lines, a first straight line L1 and a second straightline L2, which are formed in the upper wall of the building 2000, aredetermined on the basis of the image data. Then, based on therelationship between an intersection point of the two straight lines anda position of a preliminarily measuring point in the image, coordinates(X, Y, Z) of the corner part 2000 a are determined.

The position of the preliminary measuring point is identified by ahorizontal angle (direction angle) and a vertical angle from a knownpoint as viewed from a reference point.

An equation of the two straight lines is determined by applying theleast-squares method to image data variations.

The straight lines can be determined by, for example, the least-squaresmethod.

On the assumption that the equation of the straight line is y=ax+b, theabove description is given by the two straight lines, that is to say,the first straight line L1 and the second straight line L2. However,three or more straight lines may also be set so as to determine theirintersection points.

In this case, there is exhibited an effect of increasing the accuracy ofthe intersection points.

It is possible to determine two straight lines a, b by use of theleast-squares method as described below. It is to be noted that if theconditional least-squares method and/or the weighted least-squaresmethod are used as the least-squares method, the straight lines can bedetermined with higher accuracy, and thereby the coordinates can bedetermined with higher accuracy. In case of the conditionalleast-squares method, by making it a condition that, for example, theoutward appearance of the building is formed of perpendicular straightlines, the corner of the building is considered to exist on the straightlines, and a connected line is determined as a straight line. Thus, itis found that the building perpendicularly stands. The conditioningmakes it possible to minimize the influence of distortion of an imageoptical system, and also to make a calculation process easy. Moreover,it is also possible to determine the coordinates with higher accuracy byapplying the weighted least-squares method in which detection ofreceiving light on a pixel basis is taken into consideration.

Mathematical expression 1:

Solution of the least-squares method: in case of y=ax+b

$\{ {{ \begin{matrix}{{{x_{1}a} + b} = y_{1}} \\{{{x_{2}a} + b} = y_{2}} \\\vdots \\{{{x_{n}a} + b} = y_{n}}\end{matrix}\Rightarrow{\begin{bmatrix}x_{1} & 1 \\x_{2} & 1 \\\vdots & \; \\x_{n} & 1\end{bmatrix}\begin{bmatrix}a \\b\end{bmatrix}}  = {{\begin{bmatrix}y_{1} \\y_{2} \\\vdots \\y_{n}\end{bmatrix}\mspace{14mu}{or}\mspace{14mu}{AX}} = {{B{if}\mspace{14mu}{vi}} = {( {{x_{i}a} + b} ) - y_{i}}}}},{\begin{bmatrix}v_{1} \\v_{2} \\\vdots \\v_{n}\end{bmatrix} = {{\begin{bmatrix}x_{1} & 1 \\x_{2} & 1 \\\vdots & \vdots \\x_{n} & 1\end{bmatrix}\begin{bmatrix}a \\b\end{bmatrix}} = {{\begin{bmatrix}y_{1} \\y_{2} \\\vdots \\y_{n}\end{bmatrix}\mspace{14mu}{or}\mspace{14mu} V} = {{{AX} - {B{\sum v_{i}^{2}}}} = {{V^{t}V} = {{{minimum}\frac{{\partial V^{t}}V}{\partial X}} = {{0\mspace{14mu}\therefore{A^{t}{AX}}} = {{A^{t}{{B\begin{bmatrix}{\sum x_{i}^{2}} & {\sum x_{i}} \\{\sum x_{i}} & n\end{bmatrix}}\begin{bmatrix}a \\b\end{bmatrix}}} = {{\begin{bmatrix}{\sum{x_{i}y_{i}}} \\{\sum y_{i}}\end{bmatrix}a} = \frac{{n{\sum{x_{i}y_{i}}}} - {( {\sum x_{i}} )( {\sum{yi}} )}}{{n{\sum x_{i}^{2}}} - ( {\sum x_{i}} )^{2}}}}}}}}}}},{b = \frac{{( {\sum x_{i}^{2}} )( {\sum y_{i}} )} - {( {\sum x_{i}} )( {\sum{x_{i}y_{i}}} )}}{{n{\sum x_{i}^{2}}} - ( {\sum x_{i}} )^{2}}}} $

If the first straight line L1 is defined as y=a₁x+b₁ (Equation 1) and ifthe second straight line L2 is defined as y=a₂x+b₂ (Equation 2), anintersection point of these two straight lines can be virtuallydetermined as the corner part 2000 a of the building 2000, whichcorresponds to the edge.

Moreover, if the distance from the surveying instrument 1000 placed atthe reference point to the preliminary measuring point 2000 b, and dataof a horizontal angle (direction angle) and of a vertical angular, areused, it is possible to calculate three-dimensional coordinates (X, Y,Z) of the measuring point.

To be more specific, three-dimensional coordinates (X_(b), Y_(b), Z_(b))of the preliminary measuring point 2000 b can be measured on the basisof coordinates of the reference position of the surveying instrument1000, and also on the basis of the angle of orientation of thisreference position. Therefore, the three-dimensional coordinates (X, Y,Z) of the corner part 2000 a of the building 2000 which is on the sameplane can be calculated.

Incidentally, the high accuracy cannot be achieved through only theimage processing. For example, although the edges of the image of thebuilding are straight lines, data forming an image linearly variesbecause there is also a pixel that is partially received. For thisreason, if a position of the corner of the building is determined on thebasis of image data, it is not possible to achieve the accuracy that ishigher than the fineness of the arranged pixels.

What was described above is the case where the building 2000, or thelike, which is the target to be measured, is obliquely collimated. Thisis a state of substantially facing each other. When collimating aposition substantially perpendicular to the plane part, to be exact,surveying by three points is required. However, even surveying by onepoint will not produce a practical problem. In case of the one-pointsurveying, even one point suffices instead of three-point surveying.

Furthermore, in the above description, the plane part is determined onthe basis of the detection of the edges of the straight lines. However,the following method can also be used: detecting an intersection pointin a plane part, or a mere center-of-gravity position of a point, fromimage data; and thereby determining its intersection point or athree-dimensional position of the point.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be described with reference todrawings as below.

As shown in FIGS. 8 and 9, a surveying instrument 1000 is a totalstation, which comprises an electronic theodolite for detecting angles(a vertical angle and a horizontal angle), and a light-wave rangefinder.

The surveying instrument 1000 comprises the following: a telescope unit4; a frame 3 for supporting the telescope unit 4 so that the telescopeunit 4 can swing up and down; and a base 2 for supporting the frame 3 sothat the frame 3 can turn horizontally. The base 2 can be connected to atripod, or the like, through a leveling plate 5.

The surveying instrument 1000 is provided with an operation panel 7which is a part of operation/input unit 5000. A display 6 which is apart of a display unit 4300 is attached to the surveying instrument1000. Moreover, an objective lens 8 is projected from the telescope unit4.

An imager 100 is used to convert data of an image device into digitaldata. For example, the imager 100 is an electron camera such as adigital camera. This imager 100 comprises a first imager 110 for pickingup a wide-angle image, and a second imager 120 for picking up anarrow-angle image.

Here, an optical configuration of the telescope unit 4 will be describedwith reference to FIG. 10.

The telescope unit 4 comprises the objective lens 8, a dichroic mirror20, a condensing lens 41, a third half mirror 33, a first image sensor210, a second image sensor 220, and a focus lens 12.

The dichroic mirror 20 includes a first prism 21, a second prism 22, anda third prism 23. The dichroic mirror 20 includes a first half mirror 24and a second half mirror 25.

It is so devised that a light beam incident from the objective lens 8enters into the dichroic mirror 20, a measuring light beam and a part ofvisible light are reflected by the first half mirror 24, and thenthrough the condensing lens 41, an image is formed in both a first imagesensor 210 and a,second image sensor 220.

Only the measuring light beam is reflected in the second half mirror 25,and thereby the distance is measured.

After the light beam has passed through the condensing lens 41, a partof the light beam is reflected by the third half mirror 33, and itsimage is formed in the second image sensor 220. In addition, the lightbeam which has passed through the third half mirror 33 results in imageformation in the first image sensor 210.

A control processor 4000 instructs a display unit 4300 to display alight receiving signal that has been received by the first image sensor210 and by the second image sensor 220. Incidentally, the first imagesensor 210 is associated with the first imager 110, and the second imagesensor 220 is associated with the second imager 120.

The light beam which has passed through the first half mirror 24 isintroduced into an eyepiece through the focus lens 12.

Next, an electric configuration of the surveying instrument 1000according to this embodiment will be described with reference to FIG. 8.

The surveying instrument 1000 comprises a distance measuring unit 1100,an angle measuring unit 1400, a storage unit 4200, the display unit4300, a drive unit 4400, the control processor 4000, and theoperation/input unit 5000. Here, the storage unit 4200 is used to storedata, a program, and the like. The display unit 4300 and theoperation/input unit 5000 enable a user to operate the surveyinginstrument 1000.

The distance measuring unit 1100 uses a non-prism type light-wave rangefinder. The distance measuring unit 1100 comprises a light emitting unit1110 and a light receiving unit 1120. The light emitting unit 1110 emitsa distance measuring light beam in a direction of a target to bemeasured. A light beam reflected from the target to be measured entersinto the light receiving unit 1120, and thereby the distance to thetarget to be measured can be measured.

To be more specific, the distance from the surveying instrument 1000 tothe target to be measured is calculated by the time difference from thetime when the light emitting unit 1110 emits pulses of light until thelight receiving unit 1120 receives the pulses of light. It is to benoted that this arithmetic operation is executed by the controlprocessor 4000.

An angle measuring unit 1400 comprises a vertical-angle angle measuringunit 1410 and a horizontal-angle angle measuring unit 1420. In thisembodiment, a horizontal angle encoder and a vertical angle encoder areused. Each of the horizontal and vertical angle encoders includes arotor mounted on the turning unit, and a stator in which a fixed unit isformed. Incidentally, the angle measuring unit 1400 corresponds to anangle detector.

The drive unit 4400 comprises a horizontal drive unit 4410 and avertical drive unit 4420. By use of a motor, the drive unit 4400 canturn the surveying instrument 1000 both in the horizontal direction andin the vertical direction.

The control processor 4000 includes a CPU, and executes various kinds ofarithmetic operation.

Next, one example will be described. In the example, as shown in FIGS. 3and 6, three-dimensional coordinates (X, Y, Z) of the corner part 2000 aof the building 2000 which is a target to be measured are measured.

To begin with, as shown in FIG. 11, in a step 1 (hereinafter“step” isabbreviated to S), three points are properly determined as preliminarymeasuring points A, B, C on a wall surface in proximity to the cornerpart 2000 a in FIG. 3. Next, the distance measuring unit 1100 of thesurveying instrument 1000 measures the distance to the preliminarymeasuring points A, B, C and a horizontal angle and a vertical angle. Inaddition, the imager 100 picks up an image of the building 2000 which isthe target to be measured. The imager 100 allows the first imager 110 topick up a wide-angle image, and the second imager 120 to pick up anarrow-angle image. Accordingly, either of them is selected ifnecessary.

Next, in a step S2, from the image obtained by the imager 100, anoperation unit 1300 of the surveying instrument 1000 specifies straightlines in proximity to the preliminary measuring points A, B, C that havebeen measured by the surveying instrument 1000. To be more specific,straight lines forming the corner of the building 2000 are extracted.

The operation unit 1300 of the surveying instrument 1000 can emphasizeedges by use of a spatial filter such as Laplacian.

Moreover, in a step S3, the operation unit 1300 of the surveyinginstrument 1000 determines two straight lines, a first straight line L1and a second straight line L2, forming the corner of the building 2000.The straight lines can be determined by, for example, the least-squaresmethod or the conditional least-squares method.

Next, in a step S4, the operation unit 1300 of the surveying instrument1000 can determine coordinates (X, Y, Z) of the angle part 2000 a fromthe preliminary measuring points and an intersection point of the twostraight lines.

To be more specific, because the surveying instrument 1000 can measurethree-dimensional coordinates of the preliminary measuring points A, B,C, the operation unit 1300 of the surveying instrument 1000 cancalculate three-dimensional coordinates (X, Y, Z) of the corner part2000 a of the building 2000 which is on the same plane identified by thepreliminary measuring points A, B, C.

Moreover, an image of the telescope is formed as shown in FIG. 4.Accordingly, positioning a cross line to a place near from the straightline makes it possible to determine the preliminary measuring point A(α1, β1) in proximity to the first straight line L1, and the preliminarymeasuring point B (α2, β2) in proximity to the second straight line L2.Further, as shown in FIG. 5, positioning a cross line to the preliminarymeasuring point C (α3, β3) in proximity to the corner also enables thedetermination.

How to calculate the height (depth) Z will be described with referenceto FIG. 12.

An equation of a plane formed by a triangle ΔP₁P₂P₃ is expressed asbelow.a′X+b′Y+c′=Z  (Equation 3)where, if P₁ (x₁, y₁, z₁), P₂ (x₂, Y₂, z₂), P₃ (X₃, y₃, Z₃) are known,following Equation 4 holds true:

$\begin{matrix}{{\begin{pmatrix}x_{1} & y_{1} & 1 \\x_{2} & y_{2} & 1 \\x_{3} & y_{2} & 1\end{pmatrix}\begin{pmatrix}a^{\prime} \\b^{\prime} \\c^{\prime}\end{pmatrix}} = \begin{pmatrix}\begin{matrix}z_{1} \\z_{2}\end{matrix} \\z_{3}\end{pmatrix}} & ( {{Equation}\mspace{14mu} 4} )\end{matrix}$Solving this equation 4 as simultaneous equations makes it possible todetermine a′, b′, c′.

If a′, b′, c ′ are determined, the height of all vertexes of thetriangle (P₁, P₂, P₃) can be calculated by:z _(j) =a′x _(j) +b′y _(j) +c ′This is called TIN (triangular net).

FIG. 7 illustrates a building having no corner part. In this case, twoplanes orthogonal to the building 2000 are first determined. Then, onthe assumption that their straight lines are extended to form a cornerpart, its three-dimensional position is calculated, and therebycoordinates of the position are determined. Moreover, each window shownin FIG. 3 is a part bordered by straight lines. Therefore, if a windowis specified, applying an equation of the straight lines makes itpossible to identify a position of the window relative to a α surface,and a shape of the window.

In addition, if a plane part includes a straight line, specifying thestraight line also makes it possible to calculate a position and thelength of the straight line.

Moreover, if the plane part has a window bordered by straight lines,specifying the window to identify the window also make it possible tocalculate a position of the window.

Further, it is also possible to specify a straight line or a window,which is included in a plane part, by the collimation of the telescopeprovided on the surveying instrument.

Furthermore, it is also possible to specify a straight line or a window,which is included in the plane part, by pointing an image displayed onthe display unit included in the surveying instrument.

It is to be noted that a program which describes operational steps to beperformed by the operation unit 1300 of the surveying instrument 1000can be stored in an electronic storage medium such as a FD, a CD, a DVD,a RAM, a ROM, and a memory card.

In order to increase the accuracy, it is necessary to preciselycalibrate both the surveying instrument 1000 and the imager 100.

The present invention which is configured as above is a surveyinginstrument for measuring the distance to a target to be measured, ahorizontal angle, and a vertical angle by use of reflected light. It isso devised that an imager for obtaining a digital image which isassociated with both a horizontal angle and a vertical angle can beconnected to this surveying instrument. The surveying instrumentcomprises an arithmetic processing means for determining athree-dimensional position of a plane part by determining from at leastthree measuring points an equation that includes the plane part as atarget to be measured, and then by associating digital image data towhich the plane part belongs with the equation so that the plane part isidentified. Accordingly, even if non-prism measurement is used, ameasuring point in a corner part can be measured, which is a producedeffect.

INDUSTRIAL APPLICABILITY

The present invention relates to a surveying instrument, and moreparticularly to non-prism measurement that is capable of measuring ameasuring point in a corner part. An imager can be connected to thissurveying instrument. In addition, an arithmetic processing means candetermine a three-dimensional position of a plane part by determiningfrom at least three measuring points an equation that includes the planepart as a target to be measured, and then by associating digital imagedata to which the plane part belongs with the equation so that the planepart is identified.

1. A surveying instrument for measuring distance, horizontal angle, andvertical angle by use of reflected light, comprising: an imager forobtaining a digital image which is associated with a plane part; and anarithmetic processing means for calculating a three-dimensional positionof said plane part by determining an equation that includes said planepart by measuring distance, horizontal angle, and vertical angle to eachof at least three points substantially forming a triangle on said planepart; associating digital image data to which said plane part belongswith said equation so that said plane part can be identified; extractingedges of at least two intersecting straight lines forming said planepart; determining said straight lines based on image data related tosaid edges by the least-squares method or the conditional least-squaresmethod; and calculating an intersection point of said straight lines todetermine said three-dimensional position of said plane part.
 2. Asurveying instrument according to claim 1, wherein: if at least twoplane parts successively intersect with each other, edges of threestraight lines forming the angle are extracted, and on the basis ofimage data of the edges, the straight lines are determined by theleast-squares method or the conditional least-squares method, and thenthe angle which is an intersection point of the straight lines iscalculated to determine a three-dimensional position of the plane part.3. A surveying instrument according to claim 1, wherein: if the planepart includes a straight line, a position and the length of the straightline are calculated by specifying the straight line.
 4. A surveyinginstrument according to claim 1, wherein: if the plane part has a windowbordered by straight lines, the window is specified to identify thewindow to calculate a position and a shape of the window.
 5. A surveyinginstrument according to claim 1, wherein: if there is a point located onthe plane part which is the target to be measured, a center-of-gravityposition of image data of the point is determined, and then thecenter-of-gravity position is associated with the three measuring pointsto determine the three-dimensional position.
 6. A surveying instrumentaccording to claim 1, wherein: if said surveying instrument faces thetarget to be measured, an equation which includes the plane part as thetarget to be measured is determined from a measured value of one point,and then digital image data to which the plane part belongs isassociated with the equation so that the plane part can be identified,and thereby its three-dimensional position is calculated.
 7. A surveyinginstrument according to claim 3 or 4, wherein: a straight line or awindow, which is included in a plane part, is specified by thecollimation of a telescope included in the surveying instrument.
 8. Asurveying instrument according to claim 3 or 4, wherein: a straight lineor a window, which is included in the plane part, is specified bypointing an image displayed on a display unit included in the surveyinginstrument.
 9. A surveying instrument according to claim 1, wherein: theedges are extracted by use of a spatial filter such as Laplacian.
 10. Athree-dimensional measurement method used in a surveying instrument formeasuring the distance to a target to be measured, a horizontal angle,and a vertical angle by use of reflected light, said surveyinginstrument being configured so that an imager for obtaining a digitalimage in a measurement direction is connectable to the surveyinginstrument, said three-dimensional measurement method comprising:determining at least three measuring points of a plane part, and thenfor measuring the measuring points; determining an equation, whichincludes the plane part, from data of the distance and the angles of thethree measuring points obtained by the measurements; associating thedigital image data to which the plane part belongs with the equation,extracting edges of at least two intersecting straight lines formingsaid plane part; determining said straight lines based on image datarelated to said edges by the least-squares method or the conditionalleast-squares method; and calculating an intersection point of saidstraight lines to determine said three-dimensional position of saidplane part; wherein: a three-dimensional position of the plane part isdetermined from the image data that identifies the plane part and fromthe equation which includes the plane part.
 11. An electronic storagemedium such as a FD, a CD, a DVD, a RAM, a ROM, or a memory card,wherein: said electronic storage medium is used when performingthree-dimensional measurement by use of data obtained from a surveyinginstrument and an imager, which measure the distance to a target to bemeasured, a horizontal angle and a vertical angle using reflected light;and said electronic storage medium stores a program describing operationsteps for determining a three-dimensional position of a plane part bydetermining from at least three measuring points an equation whichincludes the plane part as the target to be measured, associatingdigital image data to which the plane part belongs with the equation sothat the plane part is identified, extracting edges of at least twointersecting straight lines forming said plane part, determining saidstraight lines based on image data related to said edges by theleast-squares method or the conditional least-squares method, andcalculating an intersection point of said straight lines to determinesaid three-dimensional position of said plane part; said operation stepsbeing executed by an arithmetic processing means.
 12. An electronicstorage medium according to claim 11, wherein: edges of at least twointersecting straight lines forming a plane part are extracted, and onthe basis of image data of the edges, the straight lines are determinedby the least-squares method or the conditional least-squares method, andthen an intersection point of the straight lines is calculated todetermine a three-dimensional position of the plane part.
 13. Anelectronic storage medium according to claim 11, wherein: if at leasttwo plane parts successively intersect with each other, edges of threestraight lines forming the angle are extracted, and on the basis ofimage data of the edges, the straight lines are determined by theleast-squares method or the conditional least-squares method, and thenthe angle which is an intersection point of the straight lines iscalculated to determine a three-dimensional position of the plane part.